1. Field of the Invention
The present invention relates generally to cell culture plates, and more particularly to a cell culture plate with multiple sets of wells, each set comprising two or more wells of increasing size and volume for cell or tissue culture expansion.
2. Description of Related Art
Numerous branches of biology, including the fields of immunology, microbiology, parasitology, pharmacology, toxicology, biotechnology, and biomedical engineering, routinely require large populations of pure cell or tissue cultures. Cell culturing is conducted on nutrient media in Petri dishes or, more commonly, in conventional cell culture plates having uniform well sizes. Separating, isolating, and then expanding cells or microorganisms thus typically entails transferring multiple cultures from cell culture plates with uniform well sizes to other plates having uniform well sizes with larger well volumes. At present, once cell cultures are established in a culturing medium on a cell culture plate, they are transferred from plates having 2 mL volume wells to plates with 5 mL wells, and thereafter to plates with wells having volumes greater than 5 mL, and so forth. In consequence, lab technicians and research scientists are required to monitor numerous plates for a single cell culture.
It would be desirable to have a cell culture plate having least two or more open-topped wells of increasing area and volume. This would eliminate the need to transfer cell cultures to new plates for culture expansion and would further eliminate the need to track numerous plates for a single culture. Multi-well culture plates have been devised, but existing designs serve different ends and comprise different structures. For example, U.S. Pat. No. 5,578,490 to Ubeira discloses a cell culture plate with a system for lateral diffusion of molecules across a barrier membrane. The plate comprises a lid, fit to cover a base consisting of two or more flat-bottomed open-topped wells, denominated the reservoir wells, each containing one or more smaller, open-topped diffusion wells sharing the same base as the reservoir wells. The diffusion wells communicate with the larger reservoir well which houses it via one or several slits located in the lateral walls of the diffusion wells, each slit being covered by a semipermeable membrane that permits the passage of soluble substances while retaining insoluble particles and cells. This solves the problem caused by other cell culture plates wherein the diffusion of substances occurs between a higher compartment and a lower compartment, and the two compartments are separated by a barrier membrane; in this situation microscopic observation and manipulation of the cells is difficult. However, the invention disclosed in the ""490 patent does not solve the problem of having to transfer expanding cell cultures to plates having wells with greater volume.
U.S. Pat. No. 5,972,694 to Mathis discloses a cluster plate having a plurality of non-removable wells for growing cells in vitro for use in large scale drug transport studies. The plate combines a device for supporting tissue cultures in a fluid medium with a structure that allows unfettered access to the portion of the well below the tissue culture. That is, the wells have an upper chamber and a lower chamber separated by a microporous membrane. Adjacent to each well is an access port having a separate opening in the top surface of the plate that provides direct access to the lower chamber of the corresponding well. The access port provides communication between the lower chamber and the ambient environment. The lower chamber is of a greater cross sectional area than the combined cross sectional areas of the upper chamber and the access port.
Though having a plurality of differentially sized wells, the ""694 patent does not disclose a method or an apparatus for cell culture expansion using a single cell culture plate. Accordingly, there remains a need for a cell culture plate specifically designed and adapted for cell culture expansion using a single cell culture plate.
Accordingly, the present invention is an improved cell culture plate for in vitro cultivation of cells and/or tissue cultures, said cell culture plate comprising a base member and a flat removable lid, the base having the external dimensions of a standard cell culture plate and further having multiple sets of open-topped wells. Each set of wells comprises two or more wells of increasing area and volume, and the collection of sets are preferably arranged in side-by-side columns, each column being adapted for use in cell or tissue culture expansion. The sizing and configuration of the wells enables cell culture expansion through the use of a single cell culture plate, rather than through use of a series of plates having wells of increasing size and volume.